PROJECT SUMMARY Vocal fold vibration is caused by a three-way coupling between laryngeal aerodynamics, acoustics, and tissue dynamics. Research focused on the glottic and supraglottic laryngeal regions has led to improved clinical care and medical procedures. Less understood is the role of the subglottic region in vocal fold vibration. However, the subglottis is an important part of speech production. A clear understanding of the geometry and mechanics of the subglottis will show how vocal fold vibration is affected by adverse conditions, such as subglottic stenosis, and corresponding phonosurgical treatment procedures. The goal of the proposed research is to acquire an improved understanding of the role of subglottic anatomy in voice production. This will result from pursuit of the following specific aims: Aim 1: Quantify three-dimensional adult human larynx geometry for use in voice production research. High- resolution, spatially calibrated images of adult human larynges will be collected from computed tomography (CT) and histological image sequences. Micro-CT and histological images will be obtained using excised larynges. These will be used to quantify macroscale glottic and subglottic geometric definitions, including vocal folds, cartilaginous framework, muscles, and connective tissue. The data will be made freely available to other researchers through an on-line repository. Aim 2: Explore the influence of subglottic anatomy on structural, acoustic, and aerodynamic aspects of phonation using complementary synthetic and computational models. Geometric data from Aim 1 will be used to create synthetic and computational self-oscillating laryngeal models, including glottic and subglottic regions. Models with changes in subglottic geometry and composition will be created, tested, and compared with original models. Observables include structural, acoustic, and aerodynamic data. Aim 3: Simulate the results of phonosurgical intervention through computational and synthetic model reconstruction. Patients with subglottic stenosis have CT imaging studies of the larynx available as part of their routine care. Before and after phonosurgical procedure of cricotracheal sleeve resection, the larynx will again be imaged. The images will be used for computational and synthetic model simulation and analysis. The results will be compared with preoperative and postoperative acoustic, aerodynamic, and laryngeal imaging measures. Adjustments to improve phonation will be tested using the computational and physical models. Accomplishing the above aims will impact several areas of voice care and research, including surgical treatment of voice disorders, vocal fold prosthesis and implant design, and voice production research.